Head lice

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Head lice


​The head louse is a wingless human parasite, a couple of millimetres in size, feeds on human blood and multiplies fast.  Head lice live in the hair and spread from one person to another in close contact. Treatment of head lice must be initiated immediately when head lice are detected.

Head lice spread easily through close contact by crawling from one person to another, and through hairbrushes as well as hats and scarfs.  Head lice do not fly or jump, nor are they spread by pets and other domestic animals. The small and transparent lice are difficult to see, but their eggs (nits) are quite visibly attached to the hair near the scalp. Lice multiply fast. A female louse can lay a hundred eggs during her lifetime, i.e. one month  and the eggs hatch within 10 days from laying. Head lice often cause epidemics at schools and care facilities  but they do not spread diseases. Head lice infestation has nothing to do with poor hygiene and frequent shampooing does not prevent them from spreading. Prevention is the best cure.​​


​The head lice bite your sculp and the bites are very itchy.  The bite marks look like bumps and are red.  Scratching can lead to an infection. You may also have head lice but no symptoms at all.​​


​Use a fine-toothed comb when looking for head lice and nits. Wet the hair and apply conditioner, then comb through the untangled hair twice over from the roots to the ends. If head lice are detected in a family, the hair of all family members should be checked.

Only the family members who have head lice are treated with anti-lice treatment shampoo containing permethrin or another anti-lice solution. Pharmacy staff will help you select the right product, if necessary. ​

Comb the hair thoroughly with a fine-toothed comb before and after the shampoo treatment.  Do not apply conditioner to your hair before the treatment. Dry the comb after each stroke with tissue paper to make sure the lice do not get back to the hair. Continue to comb with the fine-toothed comb at least every second day for two weeks.

Washing bedlinen as well as hats and scarfs may also help. You have to inform all those who are in contact with the person who got head lice; for instance friends and a child’s school. To prevent head lice from spreading, keep hats and scarfs tucked in the sleeve of the coat when left in coat racks.

When should you seek medical advice?

​You should seek medical advice, if

  • ​the head lice don’t disappear despite your best home-care efforts and prevention of reinfestation.​

More information

The producers of the instruction

​​​​​Emergency care professionals have produced the instruction in collaboration with Terveyskirjasto.​


Updated  22.4.2021